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Homework Help: Quantitative Titration

  1. Dec 14, 2009 #1
    If you were given a sample unknown solid acid that had a mass of 0.7 g and it was being dissolved in 50 mL of water and was being titrated with NaOH, is it possible to find the molar mass or the formula of the acid?

    Given information
    Mass of solid acid: 0.7 g
    Volume of acid solution: 50 mL = 0.05 L
    Volume of base used: 29.5 mL = 0.0295 L
    [NaOH] = 0.095 mol/L

    I was also told that this is monoprotic.
    HX (aq) + NaOH (aq) --> H2O (l) + NaX (aq)
     
  2. jcsd
  3. Dec 15, 2009 #2
    Hi,
    I would try to get the Acid dissociation constant with this little formula:
    Ka=( [A-]*[H+])/[HA]
    How many H+ were in the solution?
    How many mol are 0,7 g H+ ?= c (O)
    HA = c0 H+ - [H+].
    Then you just have to search for the specific the ka in and you have you acid.
    Greetings Firelion
     
  4. Dec 15, 2009 #3

    Borek

    User Avatar

    Staff: Mentor

    No need for acid dissociation constant, in fact it is completely unrelated to problem.

    If acid is monoprotic you can easily calculate number of moles from the neutralization stoichiometry. Then you know mass of the sample and number of moles in the sample - that's enough to calculate molar mass.

    --
     
  5. Dec 15, 2009 #4
    oh sorry.
    We leraned in our exams to calculate very different types of data with the Ka so I thought this task is similar.
     
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